Various hand-pushable garden tool devices have been recently developed as, for example, the combination seeder, furrow-forming and furrow-covering device disclosed and claimed in U.S. Pat. No. 3,774,557, granted Nov. 27, 1973. This garden tool device is excellent for use in planting small and middle sized seeds, but is relatively unsatisfactory for forming the large furrows required, for example, in the planting of potatoes, onions and other root plants or bulbs. Also, the gardent tool device disclosed in this patent does not have the flexibility of receiving a variety of different types of tools, for example, tools for cultivating and weed cutting.
Where hand power is utilized to propel a tilling device of the kind with which the present invention deals, it becomes exceedingly important to minimize the effort necessary to propel the device. Because the furrows which are formed are much deeper and wider than those formed, for example, by the garden tool device disclosed in said U.S. Pat. No. 3,774,557, the stresses and strains placed on the tilling device create difficult design problems to produce a rugged yet light-in-weight assembly which can be manually pushed with relative ease.
Hand powered tilling devices adapted selectively to receive different types and sizes of tilling tools are disclosed, for example, in some very old United States patents as, for example, disclosed in U.S. Pat. No. 57,871, granted Sept. 11, 1866, U.S. Pat. No. 88,275, granted Mar. 30, 1869, and U.S. Pat. No. 1,280,866, granted Oct. 8, 1918. The manner in which the various tools are selectively supportable and vertically adjustable on the hand-powered tilling devices disclosed in these and other tilling devices generally required the inconvenient lossening of nuts and bolts.
It is, accordingly, one of the objects of the invention to provide a hand-powered tilling device where the force required to propel the device is minimized, especially when the tilling tool is adjusted for progressively deeper penetration into the soil.
Another object of the invention is to provide a hand-powered tilling device which is made of modest sized metal parts, so it is relatively light in weight and yet can withstand the forces imparted thereto when digging relatively deep furrows without deformation or other damage thereto.
A further object of the invention is to provide a hand-powered tilling device to which different types of tilling tools can be readily attached quickly and easily. A still further object of the invention is to provide a hand-powered tilling device with depth-of-soil penetration adjusting means which can be more easily adjusted than the adjustable means of tilling devices of the prior art.